Apparatus for the air deposition of fibers in the manufacture of fibrous structures



March 1956 B. E. ANDERSQN ETAL APPARATUS FOR THE AIR DEPOSITION OFFIBERS IN THE MANUFACTURE OF FIBROUS STRUCTURES Filed 001.- 24, 1952INVENTORS:

ATTORNEXS.

United States P APPARATUS FOR THE AIR DEPOSITION F FIBERSIN THEMANUFACTURE OF FIBROUS STRUCTURES Bror E. Anderson, Park Ridge, and JackC. Leske, Chi

tcago, lll., assignors to A. B. Dick Company, Niles, Ill.,'

a corporation of Illinois Application October 24, 1952, SerialNO.-316,588 I 9 Claims. c1. 1'9-156 applicationtcomprises a cylindricalhousing havingan inletopening-in oneportion and a separating walldefining another portion in which a plurality of spaced open-1 ings' areprovided through which separated fibers are able to pass. Mounted withinthe housing for rotational movement about an axis parallel to that ofthe cylinder is a paddle. wheel, herein referred to as a scrabbler,having a plurality .of blades extending radially from the peripherythereof and in which the axis of rotation s offset 'to position theplates in closer proximity to the inner .faceof the separating wall withincrease in the spaced relation between the ends of the blades and theremainder of the walls of the cylindrical housing.

Spaced a short distance from theforaminous separating wall is acollecting wall having foramens dimensioned to separate out fibers onthe surface of the wall while the air stream passes theretlirough; Theseparating wall may be; of some particular. shape to produce a fibrouspreform or: it may Tcom'prise an endless foraminousbelt travelingin onedirection to form a continuous web of interfelted fibers on the surfacethereof.

Whensu'ction means are provided in connection with the underside of thecollecting wall, the fibers deposited on the surfaces thereof arestrongly anchored and'when the volume of air withdrawn throughthecollecting wall is greaterthan the volume which is able to passthrough the separating wall, then the deficiency is made up by a slightinflowp-of air from the surrounding'atmosphere intotthe space betweentheseparating wall" and the col-' lecting wall thereby to permit the space,to remain open to the atmosphere without interference of fiber flowor iwithout blowing the fibers out, into the room.

Inoperation, substantiallyseparated or loosely asso ciated fibers areintroduced at a predetermined rate throughdhetfeedopening into thecylindrical housing and are caused rapidly to circulate about thecylindrical housing responsive to mechanical actuation from the rap:

idly rotating (scrabbler. blades. The air, drawn into the; housing by:the scrabbler blades, and fibers are thust caused-to travel. as aconstantly moving layer over the. 1

face of the separating wall under slight positive pressure toestablish-conditions similar tothat of a shower-head whereby uniformvolumes of air and fiber are causedtopass thr'oughtthe openings of theseparating wallto the collecting wall.

It has been found in operation thatua; fairly. high percentage of {thefibers fedinto the cylindrical housing are incapable of passing throughthe separating wall for deposition re ain -a fibrousstructure on thecollecting wall. The cause for'such loss of fiber transmission isseparating wall.

ice

traceable to the formation build-up of such fiber balls would interferewith the operation of the fiber depositing system. Obviously it would beimpractical periodically to stop the operation of the' fiber depositingunit to rid the cylindrical housing of such As a result, various systemshave been devised to effect the continuous removal 'ofsuch' fiber ballsor rice.

fibers or. balls but such techniques have been found insufiicientbecause they are not only expensive and complicated in operation butthey permit a waste of fiber.

Instead of providing a more efiicient separator to eliminate the ballsof fibers from the scrabbler system, it is an object of this inventionto provide means for reducing the amount of fibers formed into suchballs or rice thereby markedly to increase the utilization of the fibersintroduced and greatly to increase the efiiciency of the fiberdepositing system.

Another object is to produce an improvement in ap 5 pa'r'atus for theair deposition of fibers to form fibrous structures, and it is a relatedobject'to provide means in'apparatus Ofthe type described which reducesto a minimum those factors whichgive rise to the formation a of fiberballs and rice from' the, separated fibers fed into the scrabblersection.

These and other objects and advantages of thisinventionwillhe'reinafterappear andfor purposes of illustration, but not of limitatioinanembodiment is shown in the accompanying drawing in which-- Figure 1 isasectional elevational view through a fiber depositing head embodyingfeatures of this invention,

and

Figure 2 is ase' ctional view taken along the line 2 2 of Figure 1. 7

It has been found that when suitable means" are provided for removingfibers caught on the ends Of the scrabbler blades,the amount of riceformed may be reduced from as much as 30 percent of the fiberintroducedto less than 0.5 percent or upto a sixty-fold reduction in theformation of such clotsand bundles;

This represents a 'marked increase in the efficiency and in theop'e'rationo'f 'th'e fib'er depositing machine. While mechanical wipersmight be used for the removal of such fibers fromthe ends of the blades,it has been found more expedientto'make use of a blade cleaning systemwhich depends upon the reaction with air and which imparts some functionin maintaining the desired turbulence of mean streams thereby to effectbetter distribut'ion of fibers in the fiber depositing head;

' Inac'cordance with the practice ofthis invention, the. end's'of theblades are kept substantially free of fibers by blasting the ends withone or more air streams positioned to engage the blades preferablyimmediately in advance of "passage into the separating wall sectionwhere the ends of the scrabbler blades approachclosest to the walls 7 ofi thefcfylindrical' housing. It is believed that it is pri{ marilywithin this area that such fiber balls and rice are formed as a rollingor'rubbing action between the fibers on the ends of the blades and thesurface of the scrabblerblades as they pass by, as for example from anumber of air nozzles arranged across the cylindrical housing in spacedapart relation or from a single air outlet in the form of an elongatenoizle for directing a substantially continuous blastof air against theends of the scrabbler l dof the separated fibers into 3 balls or ricewhich are unable to pass through the" openings in the separating walland present acritical problem of elimination, otherwise the scrabblersection would be quickly filled with such agglomerates and the A ush wni th dr wi .fibe ...depos. t ng. head. f the air deposition of dryfibers comprises an elongate cylindrical housing having an inlet opening11 extending substantially continuously across the upper portionthereof. A feed duct12communicates directly with the feed openingsubstantially throughout its length for introducing separated fibersinto the housing and for enabling a relatively large volume of air to bedrawn by the scrabbler blades or else introduced in predeterminedvolumes under positive pressure through suitable duct work incommunication With an air blower or the like, as more specificallydefined in the aforementioned application. Practically diametricallyopposite the feed opening, the cylindrical housing 19 is provided withaseparating wall section 13 having openings 14 dimensioned to permitpassage of separated fibers and preferably spaced by a distance. whichprevents fibers entering twoopenings at the same time so as to cause ablock and a source for fiber agglomeration. The separating wall ,13 mayform an integral part of the cylinder wall but it is preferred toprovide one or more separate curvilinear plates for attachment to thewall of the housing and having openings of different dimension andspacing for use with various types of fibers and lengths of fiberscalculated to secure best results.

Positioned a short distance from the separating wall but in spacedrelation therewith is a collecting wall 15 having openings dimensionedto permit passage of air or to separate out fibers from the air streamonto the surfaces thereof whereby the fibers collect in interfeltedrelation and conform to the contour of the collecting wall in theformation of a fibrous preform. When the collecting wall is a relativelyflat member adapted to form panels or webs, the wall may comprise anendless foraminous member adapted to move in one direction at a ratebalanced with the amount of fibers to produce a felted layer-of fibersof desired thickness.

The underside of the collecting wall may be in communication withductwork 16 through which air is withdrawn, as by the blower, or byother means to generate a suction which anchors the separated fibersonto the surface of the collecting wall. When the amount of airwithdrawn from the underside of the collecting wall exceeds the amountof air issuing with the fibers through the separating wall, thedeficiency is adapted to be made up by a slight inflow of air from theatmosphere into the space between the separating Wall and the collectingwall. This condition prevents fibers from being blown out into theatmosphere and provides for the smooth flow of air and fibers from theseparating wall and collecting wall. Thus, this critical area in an airdeposition system can be allowed to remain open to the atmospherewithoutcausing nonuniform distribution of fibers, agglomeration offibers into bundles or blowing fibers out into the atmosphoto. By beingable to leave this area between the-separating wall and collecting wallopen to the atmosphere, it is possible to introduce various substances,such as dry binders, or the like, onto the fibers prior to or justastheyare being deposited.

The desired movement of fibers and airfor transfer in unifOrmvOIumes anddistribution through the openings of the separating wall is effected bya mechanical scrabbler in the form of a plurality of resilient blades 20formed of rubber, metal or the like extending radially from theirmounting in the periphery-of spaccdrims 21 secured by spokes 22 to a hub23 mounted on a shaft 24 axially positioned for rotational movement inthe ends of the housing 10. The rotatable scrabbler is positioned to beoffset in the direction of the separating .Wallso that the tips of theblades are just short of the separating wall.

As the scrabbler blades rotate at high speed within the housing, thefibers and air entering the housingare caused to revolve rapidly aboutthe periphery of the housing, causing a layer of air and entrainedfibers to move constantly across the face of the separating wall underpositive pressure whereby conditions exist similar to that of ashower-head and equal volumes of air and fiberspass through the openingsof the separating wall to the collecting wall.

In the illustrated embodiment, the ends of the scrabbler blades 20 areacted upon by a continuous blade of air blasted onto the blades prior totheir passage into the area of the separating wall. The air blast meanscomprises an elongate header 25 in the form of a rectangular tubingextending through a corresponding opening 26 in the outer wall of thehousing. The header is connected by a tubular passage 27 to a source ofair under pressure and a narrow slot 28 is provided through the endportion of the header extending laterally into the housing through whichthe air issues under high pressure as a continuous blade directedradially from the housing for removing fibers caught on the ends of thescrabbler blade. It will be understood that the desired effect may besecured by a plurality of separate air inlets spaced across the housingand that all or part of such air nozzles may be adapted to reciprocateso as to secure a more complete coverage of the scrabbler blades. Itwill also be understood that the air blast may be directed at an angularrelation with the blades to sweep the fibers off the ends thereof.

It has been found in actual practice that conditions which haveheretofore resulted in the formation of rice or balls from 30 percent ofthe fibers fed into the cylinder can be reduced to about 0.5 percentmerely by modification of the same structure to embody the cleaning orfiber removing blast described herein. Thus by. the modificationdescribed, more eificient use can be made of the fiber depositing headand fibrous products can be produced with less interruption orintcrferencewith the operation of a machine and with a more efiicientutilization A further improvement in apparatus for deposition of dryfibers of an air stream circulating rapidly about the cylindricalhousing and over the face of a foraminous cylinder wall, as effected bythe mechanical scrabbler means just described or by air scrabbler meansdescribed in the copending application of James dA. Clark et:al., Ser.No. 313,316, filed on October 6, 1952, entitled Air Scrabbler System forFiber Deposition in the Manufacture of Fibrous Structures, resides inthe modification in the contour of the wall defining the interior of thehousing whereby a suction zone is generated in the fiber feed area toprevent interference with the rotational movement of the air and fibersabout the housing and'to avoid such turbulence in the fiber feed zoneas-would interfere with the smooth operation of the machine.

To achieve this result, the wall portion 30 beyond the separating walland in advance of the fiber feed opening is formed substantially toelliptical shape having a lesser radius than that of the housing so thatthe end of the wall terminates below the fiber feed opening andpreferably projects beyond a portion thereof. As aresult, the rapidcirculation of air and fibers athighspeed about the housing forms ineffect a venturi which causes a slight vacuum to be generated within thefiber feed opening smoothly and uniformly to draw the fibers and airinto the cylindrical housing for joining with the air and fiberscirculating therein.

The air blast for cleaning the blades adds to the turbulence for fiberentrainment and separation and also adds to the volume of air as willpermit the existence of more desirable conditions for effecting theshower-head principle by which uniform volumes of air and fibers arecaused to pass through the separating wall. Using the air blast, noauxiliary air beyond that drawn in bythe vacuum created by the swirlingmass in the housing need be added. Under such circumstances an airlockfeeder for the fibers, such as describedin the aforementioned copendingClark application, is unnecessary. In fact, the feed opening may be leftsubstantially open to the atmosphere and the fibers fed freely inthrough the opening.

amass? It is unnecessary to make use of a separate baffle plate toregulate the air flow within the fiber depositing head.

Instead, the desired relationship betweenwalls in,the

vicinity of the fiber inlet opening may be embodied an integral part ofthe cylindrical housing by forming fiber inlet and the wall portion ofthe housing immediately beyond the inlet.

Use may be made of the concepts described without making use of themechanical scrabblers for achieving the desired air and fiber movement.For example, the desired movement of fibersmay be achieved by the use ofair scrabbler means employing streams of air introduced at high velocityinto the housing in a radial direction toachieve the desired movement. Asystem of the type described is more-fully describedin the. Clarkapplication Ser. No. 313,316. r

It will be understood that changes may be made in the details ofconstruction, arrangement and operation without departing from thespirit of the invention, especially as defined in the following claims.

We claim: A

1. Apparatus for the air deposition of dry fiber's'in the, preparationof fibrous structures comprising a cylindrical housing havingan inlet inone wallportion through which fibers and air are fed into the housingand a separating wall in another portion having openings dimensioned topermit passage of separated fibers, a collecting wall spaced a shortdistance from the separating wall having openings dimensioned to preventpassage of fibers, a paddle wheel having a plurality of scrabbler bladesmounted for rotational movement within the housing, means forintroducing air and fibers through the inlet into the housing wherebythey are caused by the rotating paddle wheel to turn about the housingand provide a constantly moving layer of air and fibers across the faceof the separating wall whereby some of the fibers and air are caused topass through the openings in the separating wall to the collecting wallwhich separates fibers out of the air stream on the surface thereof toform the fibrous structure, and air blast means for removing the fibersfrom the edges of the scrabbler blades during r0- tational movement.

2. Apparatus for the air deposition of dry fibers in the preparation offibrous structures comprising a cylindrical housing having an inlet inone wall portion for the introduction of air and fibers and a separatingwall in another portion having openings dimensioned to permit passage ofseparated fibers therethrough, a collecting wall spaced a short distancefrom the separating wall having openings dimensioned to prevent passageof fibers therethrough, a paddle wheel having a plurality of bladesabout the periphery thereof mounted for rotational movement within thehousing, means for introducing fibers through the inlet whereby they arecaused by the paddle wheel to rotate at high velocity about the housingand form a constantly moving layer of air and fibers across the face ofthe separating wall whereby some of the fibers and air are caused topass through the openings in the separating wall to the collecting wall,and air inlet means for directing a blast of air onto the blades of thepaddle wheel in advance of the separating wall for removing fiberscaught on the edges of the blades.

3. Apparatus for the air deposition of dry fibers as claimed in claim 1in which the paddle wheel is mounted for rotational movement about anaxis parallel to that of the housing but about a center offset from thatof the housing in the direction of the separating wall whereby therotating blades are spaced a lesser distance from ,the

separating wall than from the wall defining the housing portionimmediately in advance thereof to the. inlet.

:4. Apparatus for the air deposition of dry fibers in the preparation offibrous structures comprising a cylindrical, housing, having an inlet inon e wall portion and a separating wall defining another wall portionhaving openings dimensioned to permit passage of dry fibers, acollecting wall spaced a short distance from the separating wall andhaving openings dimensioned to prevent passage of fibers therethrough, apaddle wheel having a plurality of blades mounted for rotationalmovement within the housing, means for introducing air and fibers 5through the inlet into the housing whereby they are caused by the paddlewheel to rotate at high velocity aboutthe housing and form a constantlymoving layer of air and fibers across the face of the separating wall'whereby fibers and air pass thr ough the openings of the separating wallto the collecting wall where the fibers are separated on the surface ofthe collecting wall to form the fibrous structure; the interior wall ofthe hous ing beyond the separating wall having an ellipticallyshapedportion terminating below the inlet opening to cause the stream ofair: and fibers rotating about the housing to generate a v'acuum in thefeed opening to wall spaced a short distance from the separating walland having openings dimensioned to prevent passage of fiberstherethrough, a paddle wheel having a plurality of blades mounted forrotational movement within the collecting wall where the fibers areseparated on the surface of the collecting wall to form the fibrousstructure, means for directing an air blast onto the edges of thescrabbler blades to remove fibers caught thereon, the housing wallhaving a curvilinear portion of elliptical shape of decreasing radiusbetween the separating wall and the inlet to create a suction in thefeed opening whereby air and fibers are drawn smoothly into the housmg.

6. Apparatus for the air deposition of dry fibers in the preparation offibrous structures comprising a cylindrical housing formed with acurvilinear interior wall having an inlet in one wall portion and aseparating wall defining another wall portion having openingsdimensioned to permit passage of dry fibers, a collecting wall spaced ashort distance from the separating wall and having openings dimensionedto prevent passage of fibers therethrough, a paddle wheel having aplurality of blades mounted for rotational movement within the housing,means for introducing air and fibers through the inlet into the housingwhereby they are caused by the paddle wheel to rotate at high velocityabout the housing and form a constantly moving layer of air and fibersacross the face of the separating wall whereby fibers and air passthrough the openings of the separating wall to the collecting wall wherethe fibers are separated on the surface of the collecting wall to formthe fibrous structure, said paddle wheel being positioned to rotateabout an axis parallel to that of the housing but about a center offsetfrom that of the housing in the direction of the separating wall, theinterior wall of the housing beyond the separating wall being formedwith decreasing radius and terminating below the inlet opening.

7. Apparatus as claimed in claim 6 in which the curvilinear wall is ofelliptical shape having decreasing diameter as it approaches the. inletopening thereby to generate a suction within the inlet opening.

8. Apparatus for the air deposition of dry fibers in the preparation offibrous structures comprising a cylindrical housing formed with acurvilinear interior wall having an inlet in one wall portion and aseparating wall defining another wal portion having openings dimensionedto permit passage of dry fibers, a collecting wall spaced a shortdistance from the separating wall and having openings dimensioned toprevent passage of fibers therethrough, a paddle wheel having aplurality of blades mounted for rotational movement within the housing,means for introducing air and fibers through the inlet into the housingwhereby they are caused by the paddle wheel to rotate at high velocityabout the housingand form a constantly moving layer of air and fibersacross the face of the separating wall whereby fibers and air passthrough the openings of the separating wall to the collecting wall wherethe fibers are separated on the surface of the collecting wall to formthe fibrous structure, said having an inlet in One wall portion and aseparating wall defining another wall portion having openingsdimensioned to permit passage of dry fibers, a collecting wall spaced ashort distance from the separating wall and having openings dimensionedto prevent passage of fibers therethrough, a paddle Wheel having aplurality of blades mounted for rotational movement within the housing,means for introducing air and fibers through the inlet into the housingwhereby they are caused by the paddle wheel to rotate at high velocityabout the housing and form a constantly moving layer of air and fibersacross the face of the separating wall whereby fibers and air passthrough the openings of the separating wall to the collecting wall wherethe fibers are separated on the surface of the collecting wall to formthe fibrous structure, the housing being formed with curvilinearinterior walls arranged to form a greater angle between a line parallelto theaxis of the inlet at the intersection with the interior wall inadvance of the inlet opening than between a similar line at theintersection with the interior wall portionrearwardly of the inletopening.

References Cited in the file of this patent UNITED STATES PATENTS2,136,506 Horn Nov. 15, 1938 2,152,901 Manning Apr. 4, 1939 2,218,338Manning Oct. 15, 1940 2,489,079 Clark et a1. Nov. 22, 1949 2,587,814Borkland Mar. 4, 1952

